The syntax for ')' is incorrect

[internwithquest]

I am using the following DAX formula to try and calculate the total earnings of last month one year prior to now:

Rev Last Month Last Year =

VAR LatestDate = MAX(OrderHead[InvoicePeriodDate])

VAR PrevYear = YEAR(LastDate) - IF(MONTH(LastDate) = 1, 1, 0)

VAR PrevMonth = IF(MONTH(LastDate) = 1, 12, MONTH(LastDate) - 1)

VAR Result = CALCULATE(SUM(OrderHead[CustomerTotal]), YEAR(OrderHead[InvoicePeriodDate]) = PrevYear, MONTH(OrderHead[InvoicePeriodDate]) = PrevMonth)

RETURN Result

This gives me the error "The syntax for ')' is incorrect.". 

What am I missing here?

[internwithquest · Accepted solution]

Found my error, my variable name is not the same when I call it